What Is Actinic Keratosis?
Actinic keratosis (also called solar keratosis) is a very common, sun-induced change in the skin, in which cumulative UV damage causes areas of abnormal, pre-cancerous skin cell growth. It is considered the earliest point on a spectrum that can, in a small proportion of cases, progress toward Bowen's disease or invasive squamous cell carcinoma — though most individual patches never progress, and many even resolve on their own.
Causes & Risk Factors
- Cumulative lifetime UV exposure — by far the leading cause
- Fair skin, and skin that burns easily
- Older age
- Immunosuppression, which increases both the number of lesions and the rate of progression
Signs to Look For
Actinic keratoses typically appear as rough, dry, scaly patches on chronically sun-exposed skin — the face, scalp (especially in bald or thinning areas), ears, forearms and backs of the hands. They are often easier to feel than to see, with a sandpaper-like texture, and are commonly pink, red, or skin-coloured. Multiple lesions in a sun-damaged area are common (sometimes called "field change").
When to Seek Assessment
Most actinic keratoses can be safely monitored or treated in routine care. Assessment should be sought promptly if a lesion becomes:
- Thicker, more raised, or tender to touch
- Rapidly growing
- Bleeding, ulcerating, or failing to settle with standard treatment
These features can indicate progression toward Bowen's disease or invasive SCC and warrant biopsy to clarify the diagnosis.
Treatment Options
Because the risk of any individual actinic keratosis progressing to skin cancer is low (estimated at well under 1% per lesion per year), treatment decisions balance this small risk against the practicality and tolerability of treatment, particularly where there are multiple lesions:
- Watchful monitoring — a reasonable option for a small number of stable, typical lesions, since many actinic keratoses regress spontaneously, particularly with good sun protection
- Cryotherapy — freezing individual lesions; quick and effective for a small number of discrete patches
- Topical field treatment (5-fluorouracil, imiquimod, or diclofenac gel) — applied over an area of skin over several weeks, useful where there is widespread field change rather than one or two isolated lesions
- Photodynamic therapy — a light-activated treatment, particularly useful for larger areas of field change or cosmetically sensitive sites
- Curettage — for thicker, more resistant lesions, often combined with sending the tissue for pathological examination
Prevention
Ongoing sun protection — broad-spectrum sunscreen, protective clothing and avoiding peak UV hours — is the most important measure to reduce the development of new actinic keratoses over time.